The present invention relates to a method of manufacturing loading plane border frame tubes for chairs and particularly a method that utilizes continuous roll-forming processes to roll a base material to form loading plane border frame tubes for use on chairs.
Many leisured chairs now available on the market have small sizes and light weights, and are easy to carry and store. Their prices are also relatively inexpensive. Hence they are widely accepted by consumers. Whereas they still have problems when in use.
Most leisured chairs have a loading section to support human body. The loading section generally has a loading border frame formed by a round steel tube and a seat pad made of a selected fabric or leather. The fabric or leather is stitched at the rims to form a coupling section. During assembly, the steel tube is directly inserted into the coupling section. Or the coupling section of the fabric or leather may be connected to the border frame by springs. When used for supporting people for a period of time, the stitching of the fabrics or leather could be frayed and ruptured, or the springs connecting the fabrics (or leather) and loading border frame could have elastic fatigue, or the round steel tube will result in deformation. It could become risky to users when using.
The loading border frame of conventional leisured chairs may also be made of light wood to couple with the fabric or leather coupling section. Or the fabric or leather may be stitched directly to the wooden border frame by means of staple guns. When used for supporting people for a period of time, the stitching of the fabrics or leather could be frayed and ruptured. The stapled portions also tend to rupture, or the wooden frame broken. It also incurs safety concerns to users.
The primary object of the invention is to resolve the foregoing disadvantages. The invention aims to provide a continuous roll-forming processes to roll a base material to form loading plane border frame tubes for use in chairs. When in use, the rims of the loading plane (such as loading planes made by weaving or braiding fabrics, leather, plastic sheets) are fastened to an insert element which may be directly wedged into the frame tube so that the loading plane won""t be ruptured when supporting the weight of people.
Another object of the invention is to provide formed tubes that are simple and easy to assemble to save processes and time.
A further object of the invention is to provide formed tubes with selected cross sections to complement the supporting power of the loading plane so that deformation or rupture is less likely incur to the loading plane
To attain the foregoing objects, the method for manufacturing the tubes of the invention includes to flatten and smooth steel sheets through a roller leveler, then the steel sheets are formed to semi-finished tubes by roll-forming processes through a first, a second, a third and a fourth roller calender. The semi-finished tubes then are conveyed to a high frequency generator for welding and soldering at high temperature, then are delivered to a trimming machine for finishing, and finally are transported to a fifth roller calender to proceed final roll-forming to become finished tubes for use in loading planes of chairs.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.